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Showing papers by "Louisiana State University published in 1985"


Book
01 Jan 1985
TL;DR: In this paper, the authors present a model for the formation of a dense disk in a binary system and a dense disc in an active galactic nuclei, where the disk is a source of energy.
Abstract: 1. Accretion as a source of energy 2. Gas dynamics 3. Plasma concepts 4. Accretion in binary systems 5. Accretion discs 6. Accretion on to a compact object 7. Active galactic nuclei 8. Accretion discs in active galactic nuclei 9. Accretion power in active galactic nuclei 10. Thick discs 11. Accretion flows.

2,422 citations



Journal ArticleDOI
01 Jan 1985
TL;DR: In this paper, the chemical reaction pathways to soot were investigated by experimenting with detailed kinetic models of soot formation under the conditions used in shock-tube pyrolysis experiments.
Abstract: The chemical reaction pathways to soot were investigated by experimenting with detailed kinetic models of soot formation under the conditions used in shock-tube pyrolysis experiments. The analyses of the computational results revealed a single dominant route for the main soot mass growth. Fused polycyclic aromatics play a particularly important role: their formation reactions are essentially irreversible and have the effect of “pulling” chains of reversible reactions. Hydrogen atoms reactivate aromatic molecules to radicals by abstraction reactions. The main bottleneck appears at the formation of the first aromatic ring. The model explains the time scale of soot formation and soot yields obtained in shock-tube pyrolysis of acetylene and also is in accord with product distributions observed in flames.

554 citations


Journal ArticleDOI
George O. Waring1, Michael J. Lynn1, Henry Gelender1, Peter R. Laibson1, Richard L. Lindstrom1, William D. Myers1, Stephen A. Obstbaum1, J. James Rowsey1, Marguerite B. McDonald1, David J. Schanzlin1, Robert D. Sperduto1, Linda B. Bourque1, Ceretha S. Cartwright1, Eugene B. Steinberg1, H. Dwight Cavanagh1, William H. Coles1, Louis A. Wilson1, E.C. Hall, Steven D. Moffitt, Portia Griffin, Vicki Rice, Sidney H. Mandelbaum2, Richard K. Forster2, William W. Culbertson2, Mary Anne Edwards2, Teresa Obeso2, Marguerite B. McDonald3, Aran Safir3, Herbert E. Kaufman3, Rise Ochsner3, Joseph A. Baldone3, John Lindberg3, Rudy Franklin3, Deborah Poloson3, Mike D Ostrick3, Donald J. Doughman4, J. Daniel Nelson4, J. Douglas Cameron4, Patrick Williams4, Penny A. Asbell5, Steven M. Podos5, Michael J. Newton5, George Pardos5, Norma Justin5, Hal D. Balyeat6, James C. Hays6, Wayne F. March6, Jack Whiteside6, Becky Hewett6, Douglas Corley6, Beth Kuns6, Ronald E. Smith7, James J Salz7, Douglas Steel7, Richard A Villaseñor7, Jenny J. Garbus7, Jan Reinig7, Robert C. Arends, John W. Cowden, William T. Sallee, Robert L. Stephenson, Paul Fecko, Henry J. Spiro, Vicki Roszka-Duggan, Juan J. Arentsen8, Michael A. Naidoff8, Elisabeth J. Cohen8, Nubia Cantillo8, Roy Monlux6, Michael Isaac6, Beverly J. Cosand9, Shari Swift1, Darrl Clark1, Vicki Shadix1, Jay H. Krachmer10, Robert J. Hardy11, James P. McCulley, Walter J. Stark12, Richard A. Thoft, James V. Aquavella13, Jules L. Baum13, Joel Sugar14, James S. Ware15, Michale J. Lynn1, Ronald G. Geller16, Ralph J. Helmsen16 
TL;DR: The Prospective Evaluation of Radial Keratotomy (PERK) study is a nine-center, self-controlled clinical trial of a standardized technique of radial keratotomy in 435 patients who had physiologic myopia with a preoperative refraction between -2.00 and -8.00 diopters.

332 citations


Journal ArticleDOI
01 Jan 1985-Nature
TL;DR: It is reported here that modified live Toxoplasma-containing vacuoles fail to acidify in normal macrophages, as indicated by the sensitive pH probe fluorescein.
Abstract: Toxoplasma gondii belongs to a group of highly virulent intracellular parasites that reside in host cell vacuoles which resist typical phagosome-lysosome fusion. Live Toxoplasma replicate prodigiously within modified phagocytic vacuoles formed during invagination of the host plasma membrane. In contrast, heat-killed Toxoplasma or specific antibody (heat-inactivated)-coated live Toxoplasma-containing vacuoles readily undergo lysosome fusion and digestion in normal macrophages. Of newly recognized significance to Toxoplasma survival is the microbicidal effect of phagosome acidification, which reportedly can occur independently of fusion with other acidic vesicles. We report here that modified live Toxoplasma-containing vacuoles fail to acidify in normal macrophages, as indicated by the sensitive pH probe fluorescein. In contrast, when live Toxoplasma are coated with specific antibody (heat-inactivated), they trigger phagosome acidification when entering normal macrophages. A similar acidification is observed when normal phagocytes ingest dead Toxoplasma. Extracellular Toxoplasma are highly susceptible to acidic pH conditions, indicating that the acidification block in the modified vacuoles may be important for intracellular survival.

284 citations


Book ChapterDOI
TL;DR: This chapter presents a conceptual synthesis of some related, and perhaps, previously unrelated empirical research on the so-called “contextual” “interference” effect and the inability of current theories of motor learning to explain why this effect occurs.
Abstract: This chapter presents a conceptual synthesis of some related, and perhaps, previously unrelated empirical research. The impetus for this chapter arises primarily from our recent explorations of the so-called “contextual” “interference” effect (Lee & Magill, 1983a, 1983b; Lee, Magill & Weeks, 1984; Magill & Lee, 1984) and specifically, the inability of current theories of motor learning to explain why this effect occurs.

274 citations


Journal ArticleDOI
TL;DR: In this article, a tree-generating algorithm for summarizing large data sets is presented, in combination with existing consensus techniques, identifying those portions of evolutionary history that are poorly known due to inconsistencies in the data.
Abstract: Phylogenetic trees, derived from distance measures, may be of variable reliability due to variance in the quality of the data sets from which they are produced. Such trees, therefore, are of questionable value as a means of summarizing large data sets. To improve our confidence in these trees, a jackknife technique is presented that, in combination with existing consensus techniques, identifies those portions of evolutionary history that are poorly known due to inconsistencies in the data. Such trees more accurately represent the results of a study than do current tree-generating algorithms that obscure areas of uncertainty. The approach is a simple modification of existing tree-generating methods. As an illustration, a biochemical data set is analyzed using this technique. (Tree reliability; jackknifing; consensus trees; UPGMA; Wagner trees.) Phylogenetic trees, branching sequenc-

241 citations


Journal ArticleDOI
01 Dec 1985-Nature
TL;DR: In this article, the discovery of forest beds in the Amazon Basin radiocarbon dated to the Wisconsin-Wurm glaciation is reported, which is the first dates from the last glaciation determined on Amazonian samples.
Abstract: We report here the discovery of forest beds in the Amazon Basin radiocarbon dated to the Wisconsin–Wurm glaciation. These are the first dates from the last glaciation determined on Amazonian samples. The locality is in Ecuador, at 1,100 m elevation, near the upper limit of the present Amazonian rainforest. Both pollen spectra and Podocarpus wood in the deposits suggest that vegetation comparable to the present Andean forest grew at least 700 m lower than it does now, suggesting a temperature depression of at least 4.5 °C for the Amazon lowlands.

208 citations


Journal ArticleDOI
TL;DR: A temperature-dependent shift in the free energy of a quantum oscillator interacting, via dipole coupling, with a blackbody radiation field is obtained.
Abstract: The quantum Langevin equation is used to calculate an exact expression for the free energy of a quantum oscillator interacting, via dipole coupling, with a blackbody radiation field. In particular, we obtain a temperature-dependent shift in the free energy. This result may then be used to obtain corresponding results for the energy, the partition function, and other thermodynamic quantities.

203 citations


Journal Article
TL;DR: The main activators in calcite and dolomite are Mn 2+, Pb 2+ and several rare earth elements, and the main quenchers are Fe 2+, Ni 2+, Co 2+, and Co 2+ as mentioned in this paper.
Abstract: Most carbonate petrologists consider Mn 2+ and Fe 2+ to be the only trace elements responsible for cathodoluminescence in carbonates. However, luminescence in carbonates is caused or inhibited by a number of trace elements. The main activators in calcite and dolomite are Mn 2+ , Pb 2+ and several rare earth elements. For Mn-activated luminescence in these minerals, the main sensitizers are Pb 2+ and Ce 2+ , and the main quenchers are Fe 2+ , Ni 2+ , and Co 2+ . Non-sensitized Mn-activated luminescence in calcite and dolomite occurs at a minimum concentration of 20-40 ppm, perhaps as little as 5 pm. Pb 2+ and Ce 2+ can sensitize Mn-activated luminescence at levels as low as 10 and 20 ppm, respectively. Fe 2+ , the most abundant quencher, begins to quench Mn-activated luminescence at about 35 ppm. Ni 2+ , Co 2+ and Fe 3+ quench at even lower concentrations. The quencher concentrations necessary for extinction of Mn-activated luminescence have not been determined with sufficient accuracy, and probably depend on the quencher/activator ratios. It may be misleading to assign a specific activator or quencher element to a carbonate crystal on the basis of the luminescence colour without spectroscopic measurement. Several elements can interact to produce a certain luminescence colour that is a mixture of different emission peaks. These peaks are distinctive for certain activators and/or sensitizers and may be used to identify these elements. The variable cathodoluminescence of diagenetic carbonates is commonly used to infer the pH and redox potential of diagenetic environments by means of pH/E, diagrams that contain only Mn and Fe as cations. This is permissible only if elements other than Mn and Fe are insufficiently abundant to be effective. Other important processes that lead to significant luminescence variations in diagenetic carbonates are closed- and open-system partitioning, clay mineral and organic matter diagenesis and variations in trace element supply. Considering the multitude of parameters that determine and influence the luminescence of carbonates, environmental and stratigraphie interpretations of diagenetic carbonates on the basis of their cathodoluminescence should be undertaken with extreme caution.

196 citations


Journal ArticleDOI
TL;DR: The data and clinical impression strongly suggest that hydroxylapatite has a potential as an alloplastic implant with clinically apparent acceptance by the soft and hard tissues.
Abstract: Twelve patients, 32 to 60 years of age, received a polycrystalline ceramic form of pure dense hydroxylapatite as an alloplastic bone implant material in intrabony defects following reflection of full mucoperiosteal flaps, root planing and defect-curettement. The defects were measured from an acrylic stent, using an endodontic silver point which was placed to the base of the defect. Similarly, debrided and curetted defects in the same patients were not implanted and served as controls. Recalls for documentation and plaque control were at 1, 2, and 4 weeks, and at 3, 6 and 9 months. Measurements relating to changes in defect-depth were made upon reentry at 9 months. The twelve defects, serving as controls, showed very little difference between the pretherapy and 9-month measurements. The initial mean measurement from the base of the defect to the highest alveolar crest was 4.27 mm and the 9-month mean measurement after curettage only was 3.36 mm. In terms of resolution of the original defect this amounted to 19.49% reduction, but a 0.46-mm mean loss in height of the alveolar crest provided an actual percentage fill of the original defect of 9.91%. Of sixteen experimental defects, the same initial mean measurement from the base of the defect to the highest alveolar crest was 5.18 mm and the 9-month mean measurement after grafting was 2.43 mm. In terms of resolution of the original defect, this amounted to a 53.57% reduction, but in contradistinction to the curettage sites, a mean increase in height of the highest alveolar crest of 0.61 mm gave a true percentage fill of the original defect of 66.89%. At the 9-month reentry, the implanted mass seemed to be partially "calcified" and was resistant to penetration with a probe or removal with a curette. The data and clinical impression strongly suggest that hydroxylapatite has a potential as an alloplastic implant with clinically apparent acceptance by the soft and hard tissues.

Book ChapterDOI
TL;DR: A large number of tables displaying the parameters of various randomly chosen graphs of small order are presented, many of which are obtained by substantial use of a computer.
Abstract: Our aim in this paper is to present results about random graphs with fairly few vertices In addition to theoretical results, many of which are obtained by substantial use of a computer, we present a large number of tables displaying the parameters of various randomly chosen graphs of small order

Journal ArticleDOI
TL;DR: Les auteurs ont trouve une psychopathologie significativement plus importante chez les boulimiques par rapport a des sujets normaux, plus anxieux, depressifs, nevrotiques and impulsifs.
Abstract: Utilisant le MMPI, le SCL-90, le BDI et une evaluation de l'image du corps, les auteurs ont trouve une psychopathologie significativement plus importante chez les boulimiques (N=15) par rapport a des sujets normaux (N=15), et a des sujets obeses (N=15): plus anxieux, depressifs, nevrotiques et impulsifs

Journal ArticleDOI
TL;DR: Goodness-of-fit tests were constructed using this technique for several commonly used plotting positions for the normal distribution as discussed by the authors, which were then compared on the basis of power against certain nonnormal alternatives.
Abstract: The use of the correlation coefficient is suggested as a technique for summarizing and objectively evaluating the information contained in probability plots. Goodness-of-fit tests are constructed using this technique for several commonly used plotting positions for the normal distribution. Empirical sampling methods are used to construct the null distribution for these tests, which are then compared on the basis of power against certain nonnormal alternatives. Commonly used regression tests of fit are also included in the comparisons. The results indicate that use of the plotting position pi = (i - .375)/(n + .25) yields a competitive regression test of fit for normality.


Journal ArticleDOI
01 Apr 1985-Nature
TL;DR: In this article, the authors reported the discovery of numerous curving filaments from two different stratigraphical positions in the 3,500-Myr-old Onverwacht Group of the Swaziland Supergroup.
Abstract: The Swaziland Supergroup, Barberton Mountain Land, South Africa, has long been regarded as a promising location for the Earth's oldest fossils because it includes some of the most ancient well-preserved sedimentary rocks, many of which contain carbonaceous matter. Although there have been numerous reports of microfossils from Swaziland Group rocks1–7, the biogenicity of most of the structures has been questioned8–10. Although some of the organic spheroids are probably biogenic10,11, the best early Archaean simple spheroids are generally regarded as ‘possible microfossils’10 because organic spheroids may form abiotically in several ways12. The discovery of less-simple biological morphologies is therefore important in establishing the existence of early life forms in the early Archaean. Uniformly-sized curving filaments, especially tubular ones, are difficult to explain as anything other than the fossil remains of filamentous organisms. Here we report the discovery of numerous filaments from two different stratigraphical positions in the 3,500-Myr-old Onverwacht Group of the Swaziland Supergroup. Their morphologies and abundance provide convincing evidence for the existence of bacteria- or cyanobacteria-like organisms on the Earth during the early Archaean. This supports recent reports of similar filamentous microfossils from 3,500-Myr-old rocks from Western Australia13.

Journal ArticleDOI
TL;DR: Two patients with Acanthamoeba keratitis who received a graft early in the clinical course developed a recurrence of disease in the graft, whereas the other, who received the graft 18 months after the initial symptoms, has maintained a clear corneal transplant with useful vision.

Journal ArticleDOI
TL;DR: This work investigated the relationship between both role ambiguity and role conflict--as specific forms of role stress--and job-related tension, job satisfaction, and propensity to leave, using LISREL IV, a technique capable of providing statistical data for a hypothesized population model, as well as for specific causal paths.
Abstract: Responses from four separate samples of accountants and hospital employees provided a constructive replication of the Bedeian and Armenakis (1981) model of the causal nexus between role stress and selected outcome variables. We investigated the relationship between both role ambiguity and role conflict--as specific forms of role stress--and job-related tension, job satisfaction, and propensity to leave, using LISREL IV, a technique capable of providing statistical data for a hypothesized population model, as well as for specific causal paths. Results, which support the Bedeian and Armenakis model, are discussed in light of previous research.

Journal ArticleDOI
TL;DR: Results for variable error and absolute constant error showed that random- variable practice provided strong support for the schema theory prediction, whereas blocked-variable practice provided only relatively weak support.
Abstract: Since the publication of Schmidt's (1975) schema theory of motor learning, numerous studies have assessed the variability of practice hypothesis. Of these, only research using children as subjects has provided consistent results. Findings from adult studies have been equivocal. Two experiments were conducted to assess the possibility that the schedule of variable practice during acquisition may be a clue to this equivocality, since only experiments (using adults as subjects) that have provide random variability of practice conditions have consistently supported the tenets of schema theory. Using a two movement rapid timing task, subjects learned to control their actions under one (constant) or four (variable) parameters, with variable practice conducted under either a blocked or a randomized schedule. Results for variable error and absolute constant error showed that random-variable practice provided strong support for the schema theory prediction, whereas blocked-variable practice provided only relatively weak support. Two contrasting implications of these results are discussed with respect to support versus non-support for Schmidt' schema theory.

Journal ArticleDOI
TL;DR: For most grasses, survival and weights of fall armyworm larvae fed infected leaves were significantly lower and larval duration was significantly longer compared to larvae fed uninfected leaves, suggesting resistance to herbivores may provide a selective advantage to endophyte-infected grasses in natural populations.
Abstract: The effects of endophytic fungi (Tribe Balansiae, Clavicipitaceae, Ascomycetes) of grasses on an insect herbivore were studied by feeding paired groups of larvae of the fall armyworm (Spodoptera frugiperda, Noctuidae, Lepidoptera) leaves from either infected or uninfected individuals. Perennial ryegrass infected by "the Lolium endophyte", tall fescue infected by Epichloe typhina, dallisgrass infected by Myriogenospora atramentosa, Texas wintergrass infected by Atkinsonella hypoxylon, and sandbur infected by Balansia obtecta were utilized. The endophytes of ryegrass and fescue previously have been shown to be toxic to mammalian herbivores and to deter feeding of some insect herbivores. In this study we extend the antiherbivore properties of those endophytes to the fall armyworm and demonstrate that fungal endophytes in three other genera have similar antiherbivore properties. For most grasses, survival and weights of fall armyworm larvae fed infected leaves were significantly lower and larval duration was significantly longer compared to larvae fed uninfected leaves. Resistance to herbivores may provide a selective advantage to endophyte-infected grasses in natural populations.

Journal ArticleDOI
TL;DR: In this paper, seven mathematical models of freshwater wetlands and shallow water bodies were classified by wetland type, location, and degree of nonlinearity, and rated by three new indices: articulation, accuracy, and effectiveness.

Journal ArticleDOI
08 Feb 1985-Science
TL;DR: The chief geophagical clay entering the West African market system comes from the village of Uzalla, Nigeria, and inhabitants ascribe antidiarrheal properties to the clay, and they use it in traditional medicinal preparations to counteract intestinal problems.
Abstract: The chief geophagical clay entering the West African market system comes from the village of Uzalla, Nigeria. Village inhabitants ascribe antidiarrheal properties to the clay, and they use it in traditional medicinal preparations to counteract intestinal problems. Mineralogical analyses demonstrate a striking similarity between the Uzalla village clay and the clay in the commercial pharmaceutical Kaopectate.

Book ChapterDOI
01 Jan 1985
TL;DR: The diamine putrescine (1,4-diaminobutane) is the precursor of the polyamines spermidine (Spd) and spermine (Spm) in all living systems studied to date.
Abstract: The diamine putrescine (1,4-diaminobutane) is the precursor of the polyamines spermidine (Spd) and spermine (Spm) in all living systems studied to date. In view of the functions that polyamines may have in plant growth and development (Smith 1985), it is of importance to understand the mechanisms that regulate the availability of precursor pools for the synthesis of these compounds. In most, if not all higher plants, putrescine is synthesized via two alternate routes: (1) decarboxylation of ornithine, which gives rise to putrescine directly; or(2) decarboxylation of arginine, with agmatine and N-carbamylputrescine as intermediates. The arginine decarboxylase pathway appears to be important under conditions of stress (Flores et al. 1985), whereas the ornithine decarboxylase pathway is closely correlated with rapid cell division (Cohen et al. 1982). Spd and Spm are formed by the transfer of one or two aminopropyl moieties, respectively, derived from decarboxylated S-adenosylmethionine (Tabor and Tabor 1984). There are, however, other possible metabolic fates of putrescine besides being a polyamine precursor.

Book ChapterDOI
TL;DR: In addition to pea and oat, PYRR-DH was also detected in corn, barley, soybean and broadbean, and the enzyme was inhibited by the NAD analogs thionicotinamide and aminopyridine dinucleotide.
Abstract: Both mono- and dicotyledonous species catabolize putrescine to γ-aminobutyric acid (GABA), but by two different pathways. GABA is the major labeled product in pea shoots and oil leaves fed with a 2–4 h pulse of [l,4-14C]-putrescine (Put) or [1,4- tetramethylene-14C]-spermidine (Spd), respectively.In the presence of 1-10μM gabaculine, a specific inhibitor of GABA:pyruvate-transaminase, the label appearing in GABA increase 2 to 7-fold, which indicates that the transmination reaction is a major fate of GABA formed from Put or Spd In vivo. The conversions to GABA were demonstrated in vitro in coupled assays involving diamine oxidase from pea or polyamine oxidase from oat, and pyrroline dehydrogenase (PYRR-DH). The latter enzyme from either pea or oat is strictly NAD-dependent and is specific for pyrroline. The optimal temperature (40–45°C) and pH (7.5–8.0) are similar to those of bacterial PYRR-DH. In all cases the enzyme was inhibited by the NAD analogs thionicotinamide and aminopyridine dinucleotide (0.1—1.0 mM). In addition to pea and oat, PYRR-DH was also detected in corn, barley, soybean and broadbean Di-and polyamine oxidase are released by enzymes which degrade the cell wall, while PYRR-DH remains associated with the protoplast.


Journal ArticleDOI
TL;DR: The organization of thalamic projections in the nucleus accumbens and the caudate nucleus of cats and its relation to other subcortical striatal afferents were studied with a retrograde tracing technique by use of lectin‐conjugated horseradish peroxidase.
Abstract: The organization of thalamic projections in the nucleus accumbens (NA) and the caudate nucleus of cats and its relation to other subcortical striatal afferents Were studied with a retrograde tracing technique by use of lectin-conjugated horseradish peroxidase. The study showed that the paraventricular and medial parafascicular nuclei (PF) of the thalamus project to the medial NA and the parataenial and medial PF project to the lateral NA. The ventral tegmental area and substantia nigra pars dorsalis (SNpd) project to medial and lateral NA. The midline thalamic nuclei, rostral intralaminar nuclei, ventroanterior nucleus, medial and lateral PF, lateral posterior complex, and nucleus limitans project to medial caudate nucleus. The most medial substantia nigra pars compacta (SNpc) and rostral SNpd project to medial caudate nucleus. The center median, ventrolateral, and the central lateral nuclei of thalamus, SNpc, and SNpd project to lateral caudate nucleus. These results suggest that the thalamic and subcortical nuclei known to connect with the limbic and frontal cortices project to NA and medial caudate nucleus. Those thalamic nuclei connected with the motor system project to lateral caudate nucleus. The hippocampus projects selectively to medial NA. The amygdala, raphe, and other mesencephalic nuclei project only to NA and medial caudate nucleus. The organization of hippocampal, amygdala, and other subcortical afferents suggests that NA and caudate nucleus can be separated into medial “limbic” and lateral nonlimbic “sensory-motor” compartments, A brief review of the distribution pattern of some neurotransmitters, neuropeptides, and their receptors and behavior studies provides additional support to the concept that the striatum can be divided into several subcompartments.

Patent
26 Dec 1985
TL;DR: In this paper, an independently programmable, parallel processor for electronic computers for performing mathematical and logical operations is provided having an array of arithmetic-logic units which are interconnected so as to form dynamically reconfigurable segments of arithmetic logic units within the array.
Abstract: An independently programmable, parallel processor for electronic computers for performing mathematical and logical operations is provided having an array of arithmetic-logic units which are interconnected so as to form dynamically reconfigurable segments of arithmetic-logic units within the array. These dynamically reconfigurable segments are formed by particular combinations of the arithmetic-logic units and are so combined with selective switching circuitry so as to provide the processor with its independent and parallel features.


Journal ArticleDOI
TL;DR: The authors used covariance structure analytic techniques to assess the adequacy of traditional SRC indicators for measuring political efficacy in the United States and other liberal democracies, and found that a two-factor model of a subset of these indicators fits data for the U.S. and six other countries very well, with item loadings corresponding to prevailing conceptual distinctions between internal and external efficacy.
Abstract: Political efficacy is a key concept in theories of political participation and democratic governance. This paper uses covariance structure analytic techniques to assess the adequacy of traditional SRC indicators for measuring political efficacy in the United States and other liberal democracies. Analyses indicate that a two-factor model of a subset of these indicators fits data for the U.S. and six other countries very well, with item loadings corresponding to prevailing conceptual distinctions between internal and external efficacy. In the American case the structure of the model is invariant by race, gender and political context, and the relative strength of correlations between the efficacy factors and measures of personal competence and perceived government responsiveness agrees with theoretical expectations. Although the SRC items appear to be useful measures of efficacy, simple equally weighted additive indices such as those utilized by the SRC itself are inadequate. More sophisticated measurement m...

Journal ArticleDOI
TL;DR: In this paper, the authors examined the equity returns and bond prices of firms around the dates of their placement on CreditWatch by Standard and Poor's and found that the stock market does not appear efficient as the bond market since relative bond prices continue to decline as long as seven months after a rating change.
Abstract: This paper examines the equity returns and bond prices of firms around the dates of their placement on CreditWatch by Standard and Poor's. Bond prices and equity returns for companies listed on CreditWatch are compared with a set of firms whose debt was rerated during the same time period but were never placed on CreditWatch. The evidence indicates no market reaction when firms are listed on CreditWatch with subsequent rating affirmations, but a significant reaction exists in those cases where the listing was followed by downgradings. Furthermore, the bond market does not appear so efficient as the stock market since relative bond prices continue to decline as long as seven months after a rating change.